Field of Invention
The present invention relates generally to printed circuit boards and more particularly to protoboards with a bread board style layout.
Description of the Related Art
Often when designing a circuit or creating a circuit engineers and home hobbyists use a breadboard to test the circuit. A breadboard is a board made of plastic with plastic holes to insert electronic components and wires. A breadboard consists of a perforated block of plastic with numerous tin plated phosphor bronze or nickel silver alloy spring clips under the perforations. The clips are often called tie points or contact points. The number of tie points is often given in the specification of the breadboard. Beneath the plastic holes is a circuit board having a specific layout. The layout is typically comprised of rows and columns of the tie points. Typically, the columns will be divided in half, a left half and a right half, where each hole in a row of the left half will be internally connected to the other tie points in that half column. The right half is similar. Also, there are typically power rails, where one column is powered and one is grounded.
A wire can be used to connect the power rail to any other hole. Also, integrated circuit (IC) chips can be used and placed across the left and right halves. Using a breadboard, a circuit can be built, tested, and modified without having to solder chips and other components to a printed circuit board. However, using a breadboard can be tedious and time consuming. Each wire has to be cut and striped. Even in a simple circuit that process is cumbersome, but in a complex circuit, that process takes a significant amount of time to form the connections between the parts of the breadboard that already have internal connections.
After a circuit has been tested and proven, it can be transferred to a breadboard style printed circuit board (PCB). A breadboard style PCB has similar interconnects to a breadboard, but is a PCB. The components can be transferred easily from the breadboard preserving the layout of the circuit. The components and the hookup wires are soldered to the PCB. The soldering makes the attachment more permanent. However, the hookup wires still need to be cut, striped and soldered to the PCB, which is a laborious process.
FIG. 1 shows a breadboard-style PCB in perspective view, but with the bottom copper layer exploded. PCB 99 is the board with two-sided copper layers. The top layer has holes similar to the holes on a breadboard called plated-through-holes (PTHs). The top layer PTHs are electrically connected to the bottom layer PTHs similar to the tie points in the breadboard example.
In a breadboard style PCB, the PCB layout is similar to the breadboard layout having rows and columns of PTHs that are electrically connected horizontally and divided into a left half and a right half. Also, similarly the breadboard style PCB can have a power column referred to as a power rail and a ground column referred to as a ground rail.
In FIG. 1, PTHs 1, 2, 3, 4, 5 on the bottom copper layer correspond with and are electrically connected to the PTHs 11, 12, 13, 14, 15, respectively, on the top copper layer. Power rail 66 is a copper trace connecting 1 and 2 vertically. Power rails 67, 68, 69 are additional power rails. By convention, power rails 66 and 68 are used as negative (ground) rails, while 67 and 69 are used as positive rails. Copper traces 77 and 78 are copper traces connecting PTHs 3, 4, and 5, which form a signal tie: a component lead soldered to 3 is electrically connected to component lead soldered to 4 or 5.
For ease of explanation and uncluttering of the figure not all PTHs are labeled however, the top and bottom layer corresponding PTHs are electrically connected as described above for each PTH. For example, power rail 69 corresponds to power rail 59. Power rail 59 is comprised of PTHs 51, 52, 53, 54, 55, and 56. Similarly, power rail 58 corresponds to power 68. Power rail 58 is comprised of PTHs 41, 42, 43, 44, 45, and 46. Also, the right portion of the rows are labeled and the left portion are connected in a similar configuration. PTHs 21, 22, 23 form a right portion of row 1 and are electrically connected to each other by way of the bottom copper layer shown as 74 and 75. PTH 31, 32, and 33 form the right portion of row 2 and are electrically connected to each other by way of the bottom layer shown as 72 and 73. The rest of the rows are configured similarly to row N.
Signal ties are arranged horizontally, in two banks of parallel rows. Hookup wires (not shown) are used to electrically connect separate signal ties, or to electrically connect a signal tie to a power rail. The term signal tie point is used herein interchangeably with PTH.
As shown in FIG. 1, a breadboard style printed circuit board may be implemented with a printed circuit board stack-up, without need for solder mask or silkscreen.
However, with the prior art PCB, hookup wires must be used to form connections between power rails and between PTHs that are not electrically connected.
Accordingly, what is needed is to overcome the limitations of using wires with breadboards and over the limitations of soldering hookup wire connections using PCBs. A hookup wire requires cutting, stripping and soldering the wire.